Atmospheric stability determination using fine time-step intervals for timing of aerial application

Abstract. Determination of atmospheric conditions for proper timing of spray application is important to prevent off-target movement of crop protection materials. Susceptible crops can be injured downwind if proper application procedure is not followed. In previous studies, hourly data indicated stable conditions (unfavorable for spraying) primarily between the hours of 6:00 PM and 6:00 AM during clear conditions in the hot summer months at Midsouth U.S. latitude. With the requirement of timely farm operations, sub-hourly data are needed to provide better guidelines for pilots since conditions of atmospheric stability can change rapidly. Although hourly data can be interpolated to some degree, finer resolution for data acquisition on the order of 15 minutes would provide pilots with more accurate recommendations to match up the data recording frequency of local weather stations. For the present study, temperature and wind speed data obtained at a meteorological tower are re-sampled for calculation of the Stability ratio using short time steps. High-precision determination of temperature inversion periods influencing atmospheric stability will be examined for strength, time of occurrence, and duration.